Can we drop casts from float to bool?

[Don]

grauzone wrote:
> Don wrote:
>>> In D some people have proposed to change the semantics of the "is" 
>>> operator, to make it more useful and tidy, so if you want to know if 
>>> x is a NaN you can then write if(x is nan).
>> That won't work in this case, unless you make nan a keyword. There are 
>> 2^^62 different NaNs, so a bitwise comparison will not work.
> 
> There are other cases where if and is seem to do non-obvious things, 
> that can lead to subtle bugs. If "x" is an array, if(x) checks if the 
> array descriptor is null, and not whether x has length 0.
> 
> To be consistent, I see two choices how this could be fixed:
> 1. "if" is "intelligent", then both the float and the array case should 
> be fixed to do what one would expect

What would you expect? For floats, I don't think there's ANY choice that 
makes sense.

> 2. just turn if(x) into if(x is x.init) and make "is" a bitwise 
> comparison even for floats
> 
> If way 2. is chosen, I don't think multiple NaN would be a problem. The 
> programmer just has to be aware that NaN isn't a single value. 

Surely you mean if (x !is x.init) ?
Won't work for structs.
But why bother? If you know that if (x) is true, how does that help? 
It's not float.init, but it still might be float.nan.
You still need a seperate nan test!
  "is" yields true if the value is exactly the same, and nothing else. In
> conclusion, if(x) would be about as useless for floats as it is for 
> arrays. In any way, the situation wouldn't be worse than before, but at 
> least more consistent.

I really don't think there's a solution. The only thing that makes sense 
is to disallow it completely.

But more importantly, I cannot see any reason to try. I cannot see any 
reason why the if (x) syntax is desirable for floats. I can see many 
downsides and opportunities for bugs, but I cannot see ANYTHING good 
about it at all. It's a silly thing to have in the core language.

We don't need it. Get rid of it.